1. Field of the Invention
In one of its aspects, the present invention relates to a method of cleaning fouling materials from a radiation module.
In another of its aspects, the present invention relates to a radiation module for use in a fluid treatment system, more particularly a self-cleaning radiation source module.
In yet another of its aspects, the present invention relates to a fluid treatment system, more particularly to a self-cleaning fluid treatment system.
In another of its aspects, the present invention relates to method of treating a fluid in a fluid treatment system comprising a radiation source module, more particularly to a method for treating a fluid in a manner which obviates formation of fouling materials on the radiation source module during treatment of the fluid.
2. Background of the Invention
Fluid treatment devices and systems are known. For example, U.S. Pat. Nos. 4,482,809, 4,872,980 and 5,006,244, and U.S. patent application Ser. No. 08/026,572, now U.S. Pat. No. 5,418,370 (all assigned to the assignee of the present invention), the contents of each of which are hereby incorporated by reference, all describe gravity fed fluid treatment systems which employ ultraviolet (UV) radiation to inactivate microorganisms present in the fluid.
The devices and systems described in the '809, '980 and '244 patents generally include several UV lamps each of which are mounted within sleeves extending between two support arms of the frames. The frames are immersed into the fluid to be treated which is then irradiated as required. The amount of radiation to which the fluid is exposed is determined by the proximity of the fluid to the lamps. One or more UV sensors may be employed to monitor the UV output of the lamps and the fluid level is typically controlled, to some extent, downstream of the treatment device by means of level gates or the like.
However, disadvantages exist with the above-described systems. Depending on the quality of the fluid which is being treated, the sleeves surrounding the UV lamps periodically become fouled with foreign materials, inhibiting their ability to transmit UV radiation to the fluid. When fouled, at intervals which may be determined from historical operating data or by the measurements from the UV sensors, the sleeves must be manually cleaned to remove the fouling materials. Regardless of whether the UV lamp frames are employed in an open, channel-like system or a closed system, cleaning of the sleeves is impractical.
In open, channel-like systems, the modules comprising the sleeves are usually removed from the channel and immersed in a separate tank containing a suitable cleaning fluid. In closed systems, the device must be shut down and the sleeves are thereafter cleaned by charging with a suitable cleaning fluid or by removal of the lamps and sleeves in the manner described for the open, channel-like systems. In either type of system, the operator must accept significant downtime of the system and/or invest significant additional capital to have in place sufficient redundant systems with appropriate control systems to divert the flow of fluid from the systems being cleaned.
The system described in the '370 patent is a significant advance in the art in that it obviates a number of disadvantages deriving from the '809, '980 and '244 patents. More specifically, in one of its embodiments, the system described in the '370 patent includes the provision of a cleaning apparatus for a radiation source assembly in the fluid treatment system. The cleaning apparatus comprises a cleaning sleeve engaging a portion of the exterior of the radiation source assembly and movable between a retracted position and an extended position. In the retracted position, a first portion of the radiation source assembly is exposed to a flow of fluid to be treated. In the extended position, the first portion of the radiation source assembly is covered by the cleaning sleeve. The cleaning sleeve includes a chamber in contact with the first portion of said radiation source assembly and is supplied with a cleaning solution suitable to remove undesired materials from the first portion of the radiation source assembly.
While the cleaning apparatus described in the '370 patent represents an advance in the art, it is relatively complicated and expensive to construct necessitating investment of more capital to build a fluid treatment plant. Further, in certain installations, the apparatus creates more hydraulic headloss in the flow of fluid being treated. Accordingly, it would be desirable to have a cleaning apparatus which is relatively simple and inexpensive to construct while maintaining the performance characteristics of the cleaning device described in the '370 patent.